Embodiments of the present disclosure generally relate to neurostimulation (NS), and more particularly to delivering C tactile fiber stimulation.
NS systems are devices that generate electrical pulses and deliver the pulses to nervous tissue to treat a variety of disorders. For example, spinal cord stimulation has been used to treat chronic and intractable pain. Another example is deep brain stimulation, which has been used to treat movement disorders such as Parkinson's disease and affective disorders such as depression. While a precise understanding of the interaction between the applied electrical energy and the nervous tissue is not fully appreciated, it is known that application of electrical pulses to certain regions or areas of nervous tissue can effectively reduce the number of pain signals that reach the brain. For example, applying electrical energy to the spinal cord associated with regions of the body afflicted with chronic pain can induce “paresthesia” (a subjective sensation of numbness or tingling) in the afflicted bodily regions.
SCS therapy, delivered via epidurally implanted electrodes, is a widely used treatment for chronic intractable neuropathic pain of different origins. Traditional tonic therapy evokes paresthesia covering painful areas of a patient. During SCS therapy calibration, the paresthesia is identified and localized to the painful areas by the patient in connection with determining correct electrode placement.
Recently, new stimulation configurations such as burst stimulation and high frequency stimulation, have been developed, in which closely spaced high frequency pulses are delivered to the spinal cord in a manner that does not generate paresthesias for the majority of patients, but still affords a therapeutic result. Neuropathic pain may result from lesions or diseases affecting the peripheral or central regions of the somatosensory system, and is difficult to treat. The first spinal cord stimulator as a treatment for neuropathic pain was implanted by Shealy in 1967, which was based on the gate-control theory proposed by Melzack and Wall (1965). The gate-control theory proposed that the activation of large diameter A-beta (Aβ) fibers inhibits the transmission of noxious stimuli to the brain via an inhibitory interneuron. It has been shown that electrical stimulation also may activate these large A-beta fibers with the same result. The A-beta fibers transmit information from the periphery through the dorsal root ganglion (DRG) before projecting through the dorsal column.
Other types of sensory neurons (nerve cells) transmit information from the periphery. A-delta (A-delta) fibers are small lightly myelinated fibers that transmit mechanical or painful information, and may be perceived as the sharp pain felt after injury. C-fibers are smaller and unmyelinated sensory neurons that transmit painful information to spinothalamic tract neurons (major pain pathway) and may be perceived as the dull ache after injury.
In general, conventional neurostimulation systems seek to manage pain and other pathologic or physiologic disorders through stimulation of select nerve fibers that carry pain related signals. Conventional methods of neurostimulation essentially attempt to block pain related signals by applying a continuously train of pulses to respective nerve fibers.